This invention relates to pharmaceutical containers of the type having a seal for retaining a pharmaceutical within the container during storage and shipment and for expelling the pharmaceutical when ready for use.
Containers are known for packaging pharmaceuticals for storage, shipment and later use. In many such containers, one end of a typically cylindrical glass or pharmaceutically compatible plastic housing is sealed with a septum and closure band, while the other end is initially open to permit the container to be filled with the appropriate pharmaceutical. After filling, a piston-like seal is installed in the open end of the container in order to seal to the inner volume thereof. When the pharmaceutical is to be administered, the septum is typically penetrated with a needle and the pharmaceutical is expelled from the inside of the container by translating the seal along the axis of the container in the direction of the septum end using an appropriate tool, such as a push rod.
One of the problems encountered with pharmaceutical containers of the above type lies in the contrasting requirements for the seal: during storage and shipment, the seal must provide a tight seal to prevent leakage of the pharmaceutical outside of the confined volume of the container, while during expulsion of the pharmaceutical the seal should permit smooth translation along the inner wall surfaces of the container so that the pharmaceutical is evenly expelled without abrupt changes in the flow rate through the needle. Attempts to alleviate this problem and provide smooth translatory motion of the seal include coating the inside wall surfaces of the container with a lubricant. This solution suffers from the disadvantage that the lubricant contacts the pharmaceutical and may cause contamination, depending on the nature of the lubricant and the type of pharmaceutical stored in the container.